Gauge blocks, Johansson Gauge or slip gauges are precision ground and lapped measuring standards. They are used as references for the setting of measuring equipment such as micrometers, sine bars, dial indicators (when used in an inspection role).
They are available in various grades depending on their intended use.[1].
- reference (AAA) — high tolerance (± 0.00005mm or 0.000002")
- calibration (AA) — (tolerance +0.00010mm to -0.00005mm)
- inspection (A) — (tolerance +0.00015mm to -0.0005mm)
- workshop (B) — low tolerance (tolerance +0.00025mm to -0.00015mm)
Gauge blocks
Shown at right is an image of a metric gauge block set, close examination of the set will show that the set consists of a range of varying size blocks, along with two wear blocks.
In use the blocks are removed from the set, cleaned of their protective coating (petroleum jelly or oil) and wrung together to form a stack of the required dimension, with the minimum number of blocks. The wear pieces are included at each end of the stack whenever possible as they provide protection against damage to the lapped faces of the main pieces. After use the blocks are reoiled or greased to protect their faces from corrosion.
Wringing is the process of sliding the two blocks together so that their faces lightly bond. When combined with a very light film of oil, this action excludes any air from the gap between the two blocks. The alignment of the ultra smooth surfaces in this manner permits Molecular attraction to occur between the blocks and forms a very strong bond between the blocks along with no discernible alteration to the stacks overall dimensions.
Accessory set
The pictured accessories provides a set of holders and tools to extend the usefulness of the gauge block set. They provide a means of securely clamping large stacks together along with reference points and scribers.
Gauge pins
Similar to gauge blocks, these are precision ground cylindrical bars for use in Go-NoGo gauges or similar applications.
Gauge Rollers and balls
These are supplied as sets of individual rollers or balls as used in roller or ball bearings
References
Manufacturing Engineer on a disk - Gauge Blocks
The Joy of High Tech
